Intermediate weft thread supply apparatus for looms



July 15, 1969 E. PFARRWALLER ET AL 3,455,341

INTERMEDIATE WEFT THREAD SUPPLY APPARATUS FOR LOOMS Filed Dec. @2, 1967 3 Sheets-Sheet 1 Inventors:

Erwin Pforrwoller Anatole Brun 8! WWW M ATTORNEYS July 15, 1969 RWALLER ETAL 3,455,341

INTERMEDIATE WEFT THREAD SUPPLY APPARATUS FOR LOOMS Filed Dec. 12, 1967 3 Sheets-Sheet 2- Erwin P fdrrwuller Anc'role Bru'n ATTORNEYS Inventors:

July 15, 1969 INTERMEDIATE WEFT THREAD SUPPLY APPARATUS FOR LOOMS Filed Dec. 12, 1967 E. PFARRWALLER ET AL 5 Sheets-Sheet 5 Fig. 5

Inventors.- Erwin Pforrwoller Anmole Brun In 4- W.

ATTORNEYS United States Patent 11.5. Cl. 139-422 11 Claims ABSTRACT OF THE DISCLOSURE There is disclosed a weft thread intermediate storage device including a drum mounted on the free end of a rotating shaft. The drum is rotatably mounted with re spect to the shaft so that it can remain stationary while the shaft rotates, and an arm affixed to the shaft rotates about the drum to lay coils of thread thereon. To hold the drum stationary there are provided one or more pairs of permanent magnets, each pair including one magnet on the drum and the other stationary in a frame of reference with respect to which the shaft rotates. The magnets of the pair or pairs are so disposed that for at least one rotational position of the drum, unlike poles of the two magnets of each pair face each other across an air gap through which the coils wound on the drum are pulled during picking. Particular forms of magnets and pole shoes therefore are disclosed. There is also disclosed a control circuit including a stationary photocell illuminated by a stationary light source through an aperture in the drum for that position of the drum in which the magnet pairs cooperate to provide maximum restoring force upon departure of the drum from that position. This circuit detects accumulation of excessive thread on the drum, when the aperture is obscured by turns of thread, and also departure of the drum from the desired stationary position therefor, for suitable control of loom operation.

Background of the invention The present invention pertains to intermediate weft thread storage apparatus for looms in which the weft thread bobbin remains outside the shed. Apparatus of this type is disclosed in the copending application Ser. No. 584,131, filed Oct. 4, 1966, which is assigned to the assignee hereof. In the apparatus of that application, a storage body having a surface conforming substantially to a surface of revolution is mounted for rotation but is prevented from rotation by magnetic or other means, and this body serves for the winding up of a number of turns of thread thereon by action of a weft thread supply device which rotates about this body. Then, upon picking of the weft through the shed, the thread is pulled off the free end of this body, tension being maintained by a weft thread brake. The body is restrained from rotation with the supply device, so that turns of thread can be accumulated on it, by means of eccentrically positioned weights or by magnetic means including a stationary magnet or magnets and an armature or armatures for cooperation therewith, disposed on the body.

Summary of the invention The present invention has for an object the provision of improved means to prevent rotation of the weft thread storage body, hereinafter sometimes termed a drum. Such improved restraint is achieved according to the invention by employing at least one pair of permanent magnets, one magnet being fixedly supported and the other being 3,455,341 Patented July 15, 1969 "ice supported on the weft thread storage body with their unlike poles adjacent each other across an air gap.

By the employment of cooperating pairs of permanent magnets instead of single magnets with soft iron armatures or keepers, the torque available to resist rotation of the weft thread storage body is substantially increased. Advantageously, the storage body carries a number of permanent magnets each of which cooperates with a stationary permanent magnet so as to form therewith a pair of magnets. In this way, the restoring forces or torques of the individual magnet pairs combine additively. If plural pairs of magnets are employed, special steps may be taken with respect to the dimensions, position and distribution thereof on the periphery of the storage body.

The restoring force of the permanent magnets may be increased by a combination thereof with other means to prevent rotation such as eccentric weights on the storage body, which may be provided by the magnets themselves which are supported on that body.

Brief description of the drawings The invention will now be further described in terms of a number of non-limitative exemplary embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a schematic longitudinal axial section through an intermediate weft thread storage device in accordance with the invention;

FIG. 2 is a sectional view taken on the line II-II of FIG. 1;

FIG. 3 is a fragmentary sectional view similar to that of FIG. 2, but showing an embodiment employing bar magnets and soft iron pole shoes;

FIG. 4 is a further sectional view similar to that of FIG. 2, but illustrating still another embodiment of the invention employing two pairs of bar magnets with common intermediate pole shoes;

FIG. 5 is a graph illustrating for an intermediate weft thread storage device according to the invention employing a single pair of permanent magnets, the force tending to restore the thread storage drum to equilibrium position as a function of departure therefrom; and

FIG. 6 is a diagram similar to that of FIG. 5 illustrating however the restoring force operating in an embodiment of the invention according to FIG. 4.

Description of preferred embodiments Referring to FIG. 1, the weft thread 1 is drawn from a supply bobbin 2 outside the shed (not shown) of the loom of which the apparatus of FIG. 1 forms a part. The thread passes through a first eye 3, a thread brake 4, and thence axially through a hollow shaft 7 supported at ballbearing 5 in the loom frame 6. A pulley 8 is driven by a belt 9 and is rotatably supported on the shaft 7 for rotation with respect thereto. The pulley has affixed thereto a disc 11 of ferromagnetic material constituting one-half of an electro-magnetic coupling 10. The other half of this coupling comprises electro-magnets 12 fixed in position with respect to the hollow shaft 7. Supply of current to the electro-magnets is made via two slip rings 13 and is controlled by operation of a photocell 35 (FIG. 2) in a manner to be described hereinafter.

The weft thread passes through a further eye 14 on the axis of shaft 7 and emerges from the shaft 7 at a radial bore 15. It passes thence to a thread-feeding device eccentric of the shaft, and illustratively shown as an eye 17 in the rim of a generally conical member 16 affixed to the shaft. From the eye 17 the thread is wound on a cylindrical intermediate weft thread storage drum 18. This drum is provided, in the plane of the eye 17, with a conical portion 19 of radius declining towards the right in FIG. 1, whose function is to facilitate slippage to the right of each turn wound on the drum as the next following turn is wound thereon. The result is that the turns wound on the drum gradually move to the right to build up a series of turns 20. During the picking operation the lead turn 20a and some or all of the following turns are pulled off the free end of the drum, after passing through a thread brake 21 comprising a ring having inwardly extending brushes or bristles 84 which surround and engage the conical end surface 101 of a flange 102 at the free end of the drum. The threads thus leaves the intermediate weft thread storage mechanism at the position identified as in. It then passes through a further eye 22, a thread brake 23, and a tensioning device 24. At the picking phase of the loom cycle, the end of the thread is seized by a gripper shuttle 25 and is pulled through the shed. With this construction the thread is not subjected to any further twisting. After it is picked through the shed, the thread is held by a thread clamp not shown and is cut off on the picking side of the loom by means of a shear. The new weft thread end so for-med is then grasped by the next gripper shuttle for the next pick.

The drum 18 is rotatably supported at ball-bearings 26 on a stub 27 constituting an extension of the hollow shaft 7. By means of the permanent magnets 28 on the drum, which according to the invention cooperate with magnets 30 on the stationary magnet carrier 29, the drum is prevented from rotating.

FIG. 2 illustrates a construction according to the invention employing three pairs of magnets. As indicated by the dashed line showing, two further such pairs may be provided. This embodiment employs U-shaped or horseshoe permanent magnets in pairs, one magnet 28 of each pair being supported on the drum 18 and the other magnet 30 being supported on the carrier 29. In each pair, oppositely signed poles face each other across the air gap 31 between drum and carrier, so that their fluxes cooperate within each pair of magnets and constitute a closed magnetic circuit. The two poles of both magnets of each pair subtend the same angle 1 at the cylindrical axis of the drum, and this interval is desirably the same for all magnet pairs. The adjacent, magnetically opposite poles of circumferentially adjacent magnets on the drum, and of circumferentially adjacent magnets on the carrier, are separated by an angular interval t The two angular intervals t and 1 are made to be the same so that on the periphery of the drum and on the carrier, magnetically opposite poles are disposed successively at the constant angular interval t *=t It is evident that FIG. 2 illustrates a position of stable magnetic equilibrium for the drum 18 and carrier 29, any rotation of the drum with respect to the carrier about the axis of the drum (which coincides with that of the shaft 7 in FIG. 1) being opposed by a restoring force due to the consequent increased separation, obliquely across the gap 31, of the opposite poles of magnets 28 and 30 in each pair, which opposite poles attract each other. Other positions of stable magnetic equilibrium, but of smaller restoring force exist, in fact four more, with three pairs of magnets. These are however positions of lesser magnetic restoring force. In two of them only two magnets 28 are opposite magnets 30, and in the other two only one magnet 28 is opposite one magnet 30. The construction of FIG. 2, in which on the drum (and hence on the carrier also) circumferentially successive poles are of opposite sign is advantageous in that restoring forces of the same clockwise or counterclockwise sense (and which thus add together) are produced at all pairs of cooperating magnets on any departure of the drum and carrier, either from positions of stable equilibrium like the one shown or from positions of unstable magnetic equilibrium in which adjacent poles across the gap are of opposite sign.

The center of gravity of the system of magnets 28 supported by the drum is located approximately at the point 32 in FIG. 2. The magnets are of dense material, more dense than the remainder of the drum which may be of a light metal, or of a synthetic material or of wood or other material which is light in weight and of low magnetic permeability. Consequently, the center of gravity of the drum as a whole is located at the point marked 33. For the position of stable magnetic equilibrium illustrated in FIG. 2 in which the maximum restoring force is available (due to the cooperation of each magnet 23 with a magnet 30), the center of gravity 33 is moreover located vertically beneath the axis of rotation of the cylinder. By virtue of this disposition of the center of gravity of the drum including magnets 28, a gravitational restoring force is provided to supplement the magnetic restoring force. The operation of the forces of gravity and of the magnetic restoring forces consequently are combined.

The center of gravity 33 may be moved even farther eccentrically of the drum axis and beneath that axis by provision of the cut-out 34 for the light beam of a photoelectric control circuit on the magnetic coupling 10. A light source 35 .and a photocell 36 are disposed in the limbs of the magnet carrier 29, and the drum is apertured as indicated at 34 to afford a path for passage of light from the source to the photocell when the drum is in its position of maximum stable magnetic equilibrium illustrated, each magnet 28 cooperating with a magnet 30. So long as the light beam impinges on the photocell, current is permitted to pass at slip rings 13 (FIG. 1) to excite the magnetic coupling 10 so that the shaft 7 is effectively driven by the pulley 8 through the belt 9 in constant rotation. The weft thread supply eye 17 is carried with the shaft, and thread is continuously wound onto the drum. As soon as the thread reaches the opening 34 with its lead turn 20a and obscures or prevents the passage of light to the photocell, the magnetic coupling 10 will be disengaged. The winding process is accordingly interrupted until the next pick, at which time the thread is pulled off the drum to uncover the opening 34 whereupon the photocell restarts the winding process. In this construction therefore the photocell circuit, of which elements 35 and 36 are shown, controls the process of winding the thread on the drum. The light beam moreover passes through the aperture 34 in the drum 18 only when the latter is in the position of maximum stable equilibrium, providing maximum restoring force upon departures of the drum therefrom. When the drum departs from this position, the light beam is interrupted and the winding process is thereby stopped. Consequently, there is made available a control which holds the storage body in the optimum position of maximum available restoring force. If the drum rotates away from that position, the intermediate weft thread storage apparatus is interruped in operation and, if desired, the loom itself may be stopped.

Another embodiment of the invention, employing bar magnets, is illustrated in FIG. 3. In this figure, reference character 37 denotes a permanent-magnet disposed in the drum 18 while reference character 39 denotes a per,- manent magnet disposed in the stationary magnet carrier 29. The magnets 37 and 39 constitute a pair of magnets whose magnetic circuit is closed through the pole shoes 38 and 40 and the gap 31. More than one such magnet pair may 'be provided. This construction has, with the advantage of physical compactness, the same operation as that of FIG. 2 employing horseshoe or U-shapedpermanent magnets 28 and 30.

The compactness of construction available with bar magnets is further illustrated in the embodiment of FIG. 4. Here, in accordance with another feature of the invention, the adjacent poles of circumferentially adjacent magnets on the drum, and also on the carrier, have the same polarity. Two pairs of permanent bar magnets are shown, each including a magnet 37 on the drum and a magnet 39 on the carrier. The magnetic circuit of each pair is completed, across the air gap, with the aid of a pole shoe 38, a pole shoe 40', a pole shoe 41, and a pole shoe 42, the pole shoes 41 and 42 being common to the two pairs of magnets. The pole shoes may be made of soft iron. With the construction, and by virtue of the features thereof just described, the angular interval t of FIG. 1 which separates circumferentially adjacent magnet pairs is substantially eliminated. The length of the 'bar magnets themselves may be made smaller than the middle portion joining the ends or poles of the U-shaped magnets of FIG. 2.

FIG. 5 indicates, for an embodiment of the invention including a single pair of permanent magnets, the approximate variation of the tangential restoring force operating on the drum as a function of its departure from the single available position of stable magnetic equilibrium.

The magnets may be either of horseshoe or of bar type.

With suitable dimensioning thereof, these two forms of magnets may be magnetically equal. The abscissae of the curve represent, for example in terms of the embodiment of FIG. 3, angular displacement of the magnet 37 and hence of drum 18 with respect to the stationary magnet 39 and hence with respect to carrier 29. The origin of abscissae represents the position of stable magnetic equilibrium which is illustrated in FIG. 3. Positive abscissae thus represent positions in which the drum has been rotated counterclockwise, and vice versa. Positive ordinates represent tangential restoring force clockwise while negative ordinates represent counterclockwise tangential restoring force. The angular separation on centers of the two poles of either magnet is indicated at t. Since the curve passes through the origin from the third to the first quadrant, the crossing of the axis of abscissae at the origin represents a point of stable equilibrium. In contrast, the passages of the curve through zero ordinate values at positions of approximately plus and minus angular displacement 23 indicate unstable equilibrium points, at which like-signed magnetic poles on the stationary and movable magnets are approximately opposite to each other. These two null crossings are not, however, displaced from the origin by exactly the angular separation of the poles.

FIG. 6 shows in similar fashion the variation of the available tangential restoring force in the case of a construction according to FIG. 4 having a primary stable equilibrium position at an abscissae value of zero and secondary stable equilibrium positions at displacements of 2t and +2t. Unstable points of equilibrium are at the abscissae value plus t and minus I.

The invention is not limited to the embodiments hereinabove described. Rather, for example, the permanent magnet pairs may be disposed axially instead of circumferentially of the drum, for example, on an element of the surface of the drum. They may have varying pole separations in order to achieve a different variation in restoring force with angular departure of the drum from its equilibrium position. The permanent magnets and optionally the pole shoes may be completely or partially coated with, or embedded in, a material having low magnetic permeability. Partial such coatings are indicated in FIG. 3 at the reference characters 43 and 44. The operation of the magnets may moreover be adjusted by application of suitably shaped and disposed armatures of magnetically soft and permeable material. The drum 18 may be solid or hollow.

The invention thus provides intermediate weft thread storage apparatus for looms in which the weft thread bobbin remains outside the shed. In the embodiment of FIG. 1, this apparatus comprises a frame, which may be the frame 6: of the loom or a part thereof or afiixed thereto, a body 18 having an exterior surface conforming substantially to a surface of revolution, a shaft 7 and eye 17 rotatable with respect to the frame to wind a thread onto that body, bearings 2-6 supporting the body from that shaft for rotation with respect thereto, and at least one pair of permanent magnets 28 and 30 to restrain that body from rotation, one of those magnets being supported on the body and the other being supported on the frame to form with that one magnet, for one position of the body, a magnetic circuit closed across an air gap. The axis of rotation of the body 18 with respect to the shaft 7 (these two axes being desirably coaxial) is inclined to the vertical and is desirably horizontal. The center of gravity of the body 18 (including the magnets thereon) is eccentric to that axis, the position of mechanical equilibrium of the body about that axis coinciding substantially with that one position of the body. These and other features of the invention are set forth in the appended claims. The invention is however not limited to the embodiments hereinabove described. Rather, the invention comprehends all modifications of and departures from those embodiments prop erly falling within the spirit and scope of the appended claims.

We claim:

1. Intermediate weft thread storage apparatus for looms in which the weft thread bobbin remains outside the shed, said apparatus comprising a frame, a body having an exterior surface conforming substantially to a surface of revolution, means rotatable with respect to said frame to wind a thread onto said body, means supporting said body from said rotatable means for rotation with respect thereto, and at least one pair of permanent magnets to restrain said body from rotation, one of said magnets being supported on said body and the other being sup ported on said frame to form with said one magnet, for one position of said body, a magnetic circuit closed across an air gap.

2. Apparatus according to claim 1 wherein the axis of rotation of said body with respect to said rotatable means is inclined to the vertical and wherein the center of gravity of said body is eccentric to said axis, the position of mechanical equilibrium of said body about said axis coinciding substantially with said one position of said body.

3. Apparatus according to claim 1 including a plurality of pans of permanent magnets, each of said pairs including a magnet supported on said body and a magnet supported on said frame, the magnets on said body being non-symmetrically positioned with respect to said axis.

4. Apparatus according to claim 3 wherein the magnets on said body are disposed about the periphery of said body and wherein the angular spacing, about said axis, of the poles of said magnets on said body is substantially uniform.

5. Apparatus according to claim 1 wherein said magnets are of horseshoe shape.

'6. Apparatus according to claim 4 wherein the angular separation, about said axis, of adjacent poles on adjacent of the magnets on said body is substantially uniform and substantially equal to said angular spacing.

7. Apparatus according to claim '6 wherein adjacent poles of adjacent of the magnets on said body are of opposite sign.

8. Apparatus according to claim 1 wherein said magnets are of bar type, said apparatus further including pole shoes disposed adjacent each end of each of said magnets and extending to the vicinity of said air gap.

9. Apparatus according to claim 8 including a plurality of pairs of permanent magnets, each of said pairs including a magnet supported on said body and a magnet supported on said frame, the magnets on said body being disposed about the periphery of said body, circumferentially adjacent of said magnets on said body having adjacent poles of like sign, the pole shoes between at least two circumferentially adjacent ones of said magnets being common to the circumferentially adjacent magnets.

10. Apparatus according to claim 1 wherein said body includes an aperture for the passage of a light beam therethrough, said apparatus further including a light source and photocell disposed on said frame for the passage of light from said source to said cell through said aperture in said one position of said body, and means to control rotation of said rotatable means in response to illumination of said photocell.

11. Apparatus according to claim 1 wherein each of said magnets is at least partly covered With material of low magnetic permeability.

References Cited UNITED STATES PATENTS 2,716,007 8/1955 Scott 139-122 3,131,729 5/1964 Leysinger 139-122 3,225,446 12/1965 Sarfati et a1. 139-122 3,263,705 8/ 1966 Rossmann 139-224 HENRY S. JAUDON, Primary Examiner US. Cl. X.R. 66--132 

